A blood-based ante-mortem method for estimating PFOS in beef from contaminated dairy cattle

Authors: JOHNSTON, JOHN - Colorado State University; EBEL, ERIC - Food Safety Inspection Service (FSIS); WILLIAMS, MIKE - Food Safety Inspection Service (FSIS); ESTEBAN, EMILIO - Food Safety Inspection Service (FSIS); Lupton, Sara; SCHOLLJEGERDES, ERIC - New Mexico State University; IVEY, SHANNA - New Mexico State University; POWELL, MARK - US Department Of Agriculture (USDA); Smith, David

Submitted to: ACS Agricultural Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2023
Publication Date: 9/20/2023
Citation: Johnston, J.J., Ebel, E., Williams, M., Esteban, E., Lupton, S.J., Scholljegerdes, E., Ivey, S., Powell, M., Smith, D.J. 2023. A blood-based ante-mortem method for estimating PFOS in beef from contaminated dairy cattle. ACS Agricultural Science and Technology. https://doi.org/10.1021/acsagscitech.3c00102?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as.
DOI: https://doi.org/10.1021/acsagscitech.3c00102?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as

Interpretive Summary: Forever chemicals or ‘PFAS’ compounds are environmental contaminants sometimes found in agricultural areas. These compounds have contaminated water and feed sources of food animals. For example, a large dairy herd in the western United States was exposed to PFAS contaminated feed and water to the extent that neither milk nor meat from the affected animals could be marketed. Unfortunately, very little is known about PFAS residue accumulation and depletion from cattle after exposure to environmental PFAS sources, especially in edible tissues such as muscle. Additionally, there are no methods to predict levels of PFASs in meat after live animal exposures. To gather data supporting the construction of an accumulation and depletion model, PFOS (a specific PFAS chemical) was measured in plasma and muscle samples from 28 dairy cows sourced from a PFAS contaminated farm. Plasma PFOS levels were highly correlated to those in muscle and a model was developed to predict muscle PFAS concentrations based on plasma values. Further measurements were used to estimate the time required to deplete PFOS from muscles of animals after contaminated feed and water sources were removed. These data will be useful to regulators and risk assessors who determine the fate of food animals exposed to PFAS contaminates.

Technical Abstract: A blood-based screening method was developed to facilitate ante-mortem screening of dairy cattle suspected of containing elevated concentrations of perfluorooctanesulfonic acid (PFOS) in their muscle tissue. The collection and subsequent laboratory analyses of 28 paired blood plasma and muscle samples from PFOS-exposed dairy cattle provided the PFOS plasma and muscle data to develop a model to estimate muscle PFOS concentrations based on plasma PFOS concentrations. The blood-based ante-mortem screening approach could be applied to predict whether beef (skeletal bovine muscle) from suspect cattle populations (or sub-populations) exceeds a particular level of concern. The data analyses indicated that the relationship between muscle and plasma PFOS concentrations differed by the class of dairy cattle (heifer, lactating, and dry) and the duration of removal (withdrawal time) from exposure to PFOS. A plasma depletion model also was developed to evaluate the estimated withdrawal time required to reduce PFOS in dairy cattle muscle to below an identified level of concern. The model indicated complex PFOS plasma depletion dynamics with a non-constant rate of depletion. The required withdrawal time also depends on the initial concentration distribution (which differed between heifers and lactating/dry cows) and the identified level of concern.